Production of hydrocarbon resins and products resulting therefrom

ABSTRACT

Hydrocarbon resins having an increased softening point are obtained by a process featuring the sequential steps of: isomerizing the 2-methylbutene-1 component of a branched olefin modifier stream whereby its 2-methylbutene-2 content is enriched; polymerizing a feedstock consisting of the mixture of said enriched modifier stream and a piperylene rich feed stream; and, recovering said hydrocarbon resin with properties enhancing its utility for adhesive applications.

The invention relates to an improved process for the production ofhydrocarbon resins. More particularly, it relates to the isomerizationof an olefin modifier stream prior to its incorporation into thefeedstock utilized for synthesis of a hydrocarbon resin and to the resinproducts resulting therefrom.

BACKGROUND OF THE INVENTION

It is taught in U.S. Pat. No. 3,577,398 that a mixture of piperylene and2-methylbutene-2 polymerizes in the presence of a metal halide catalystto form a series of hydrocarbon polymers which are very useful in anumber of commercial applications requiring resinous materials.

One particular application is as components of industrial adhesives. Forthe pressure sensitive adhesives, for example, increasing the softeningpoint of the resinous component improves the adhesive peel strength andelevated temperature response of the adhesive.

Conventional sources of piperylene mixtures used to produce theseresinous hydrocarbon products are crude feed streams derived from steamcracked naphthas and catalytically cracked distillate streams containinglarge quantities of olefins in the C₅ to C₁₀ ranges (see U.S. Pat. Nos.2,753,325 and 2,753,382). Streams generally have large amounts of otherunsaturated hydrocarbons, particularly hydrocarbons containing from 4 to6 carbon atoms. Representative examples of such hydrocarbons are2-methylbutene-1, 3-methylbutene-1, pentene-1, pentene-2, and isoprene.According to U.S. Pat. No. 3,577,398 up to about 50 weight percent ofsaid unsaturated hydrocarbons based on the weight of the piperylene2-methylbutene-2 mixture can be present without deleteriously modifyingthe polymerized resin. The primary unsaturated hydrocarbons in thesefeed streams are pentene-1, 2-methylbutene-1, t-pentene-2, c-pentene-2,3-methylbutene-1 and cyclopentene.

It is known that mono-olefin feedstocks can be usefully isomerized bydouble bond migration to convert 2-methylbutene-1 and/or3-methylbutene-1 to 2-methylbutene-2 and pentene-1 to cis- andtrans-pentene-2 (see U.S. Patents: Nos. 3,151,179; 3,268,617; 3,290,404;and 3,920,765).

It is desirable to obtain hydrocarbon resins with lower molecularweights but without detrimental loss of softening points in view of thebetter high temperature properties the higher softening pointcontributes in the end use formulations with other polymers.

It is therefore an object of this invention to provide a process for thepolymerization of olefins obtained from a crude feed stream obtainedfrom the cracking of petroleum fractions whereby hydrocarbon resins oflower molecular weight are obtained.

STATEMENT OF THE INVENTION

It has been discovered that the presence of branched olefins withinternal double bonds lead to higher resin softening points, otherfactors being equal, in the aluminum chloride-catalyzed polymerizationof C₅ olefins and diolefins.

It has been further discovered that the terminal olefins, branched atthe unsaturation, e.g. 2-methylbutene-1, occurring in the steam crackednaphthas and in catalytically cracked olefin streams, can be isomerizedto the more desirable internal double bonded olefin isomer, e.g.2-methylbutene-2 isomer, by passing the crude feed stream over an acidicsolid catalyst, preferably a sulfonic acid resin or so-calledion-exchange resin. The resin is preferably insoluble and of themacrorecticular type, giving ready access to the internal acid sites.

Thus, in accordance with the object of this invention, there has beenobtained a process for the preparation of a polymeric resinouscomposition comprising from 40 to 50 weight percent units derived frompiperylene, 15 to 20 weight percent units derived from 2-methylbutenesand the balance derived from other olefinic compounds having five to sixcarbons, said 2-methylbutenes being present as the 2-methylbutene-2isomer and the 2-methylbutene-1 isomer and in a weight ratio of formerto latter greater than 10, preferably 15 to 100, optimally from 18 to30, whereby said composition has a melting point of from 90° C. to 100°C. comprising the steps of:

(a) isomerizing the 2-methylbutene-1 component of a branched olefinmodifier stream to provide a branched olefin modifier stream enriched,preferably 2-methylbutene-2, by 300 to 600 weight percent, in thecomponent;

(b) admixing said enriched modifier stream and a piperylene rich feedstream to form a feedstock for resinification;

(c) thereafter catalytically polymerizing said feedstock in the presenceof aluminum halide catalyst; and,

(d) recovering the resulting hydrocarbon resins.

In a preferred sense, one admixes from 2 to 10 wt. percent of thebranched olefin enriched modifier stream with the piperylene rich feedstream in order to provide the feedstock to be subjected tocatalytically induced polymerization to provide the hydrocarbon resin.

DETAILED DESCRIPTION OF THE INVENTION

As seen from the above, the invention has combined the procedures ofisomerization and polymerization in sequence to synthesize a crudecracked feedstock into a hydrocarbon resin having highly usefulproperties for sealing applications, such as pressure-responsive sealingof adjacent surfaces between which said resin mixed with such rubbers asnatural rubber, polyisoprene, block polymers of styrene and isoprene,etc. is positioned.

Isomerization of the branched olefin modifier stream (available fromsteam cracked naphtha or catalytically cracked olefins) is provoked bypassing the modifier stream over an acidic solid catalyst. Preferably,the acidic solid catalyst is strongly acidic polymer such as nuclearsulfonated polystyrene or copolymer of styrene and divinyl benzene.Optimally, the catalysts most suited for this invention are themacroeticular type sulfonated resins which are made by including in thepolymerization of, for instance, the styrene and divinyl benzene, aninert material which is eventually washed out leaving large voids in theresins, such as macroreticular pores. After these macroreticularion-exchange, for instance, styrene divinyl benzene resins, areprepared, they are treated with sulfuric acid to obtain the particularsulfonated ion-exchange resins useful as catalysts in this invention.The sulfonic acid groups are attached to the benzene nuclei of theresins.

Examples of some sulfonated macroreticular styrene-divinyl benzeneresins of the type described for use in this application are MSC-1-H bythe Dow Chemical Company and XN-1005, XN-1010 and XE-284 and AmberlystIR-15 (preferred for use herein) by Rohm and Haas Company. The resincatalyst is employed at moderate temperatures of 10° to 70° C.,preferably at 20° to 50° C. At too high temperatures, ca 75° to 100° C.,formation of dimers of isoprene and the methylbutene-1 and -2 olefinsoccurs with loss of desirable materials and color development in theproduct. Residence times vary with conversion desired and agitationprovided. In an agitated system, a ratio of one part catalyst to fiveparts olefin is sufficient if maintained at 35° to 40° C. for one hour.In flow systems where the catalyst is in a fixed bed, longer residencetimes are necessary, say 1 volume olefin/volume catalyst/hour at 40° C.although generally from 0.5 to 5.0 volume of olefin/volume ofcatalyst/hour is useful depending on the temperature in use.

The crude cracked streams from steam cracked naphtha generally have from4 to 10 weight parts of 2-methylbutene-1 per weight part of2-methylbutene-2 whereas the crude stream from catalytically cracked C₅to C₁₀ olefins has from 1 to 2 weights of 2-methylbutene-1 per weightpart of 2-methylbutene-2. The isomerization process as practicedaccording to this invention reduces the weight part of 2-methylbutene-1to less than 1.0, preferably from 0.5 to 0.1, optimally less than 0.25,per weight part of 2-methylbutene-2.

A naptha produced by stream cracking contains large amounts ofdiolefins, olefins, aromatics, and some paraffins. The C₅ fraction (18°to 60° C.) from such a naphtha contains 15 to 20 weight percentisoprene, 10 to 15 weight percent cyclopentadiene, 10-15 weight percentpiperylene, 5 weight percent other diolefins, 15-20 weight percenttertiary olefins, 20-25 weight percent normal olefins, and 2 to 5 weightpercent paraffins.

By using an initial, mild thermal soaking of the C₅ ⁺ fractioncontaining olefins, diolefins, cyclic diolefins, and aromatics at atemperature of 38° to 120° C. and sufficient treating time, thecyclopentadienes are dimerized and are removed as the dimers from thebottom of a distillation tower. This tower is operated to prevent anysubstantial depolymerization of the cyclodienes. The overhead,consisting of the undimerized portion, contains chiefly olefins anddiolefins and aromatics, including the isoprene. Isoprene is recoveredfrom the 16° to 38° C. fraction by extractive distillation. Theremaining C₅ fraction from isoprene extraction feed preparation containsmajor amounts of pentene-1, cis and trans pentene-2 and2-methylbutene-1, and smaller amounts of isoprene, piperylene and2-methylbutene-2. It is this stream that is usually treated by theprocess of this invention.

Alternatively, the naphtha fraction from catalytic cracking whichcontains 2-methylbutene-1 and 2-methylbutene-2 in roughly equal amounts,can be treated in a similar fashion with the aforementioned sulfonicacid resins.

This isomerized enriched modifier stream is thereafter subjected to thepolymerization step. The enriched modifier stream can be treated priorto the polymerization step to enhance its purity and/or admixed with another diluent, e.g. benzene, heptane, or mixtures thereof in amountsnecessary to achieve the desired results.

The enriched modifier stream, isomerized in accordance with thisinvention, is readily polymerized after its combination into, generallyin amounts of 2 to 10%, a piperylene rich stream by the presence of analuminum halide, e.g. aluminum chloride catalyst, more generally ananhydrous metallic halide catalyst.

Representative examples of such catalysts are fluorides, chlorides,bromides, and iodides of metals such as aluminum, tin, and boron. Suchcatalysts include, for example, aluminum chloride, stannic chloride andboron trifluoride.

In carrying out the polymerization reaction, the hydrocarbon mixture isbrought into contact with the anhydrous metal halide catalyst.Generally, the catalyst is used in particulate form. Generally, aparticle size in the range of from about 5 to about 200 mesh size isused although larger or smaller particles can be used. The amount ofcatalyst used is not critical although sufficient catalyst must be usedto cause a polymerization reaction to occur. The catalyst may be addedto the olefinic hydrocarbon mixture or the hydrocarbon mixture may beadded to the catalyst. If desired, the catalyst and mixture ofhydrocarbons can be added simultaneously or intermittently to a reactor.The reaction can be conducted continuously or by batch processtechniques generally known to those skilled in the art.

The reaction is conveniently carried out in the presence of a diluentbecause it is usually exothermic and the product is viscous. However,with adequate mixing and cooling, the temperature can be controlled andreaction conducted with only sufficient diluent to maintain goodtransfer out of the heat of polymerization. The diluent may beintroduced as a component of the feedstock for resinification, e.g. inthe example benzene is introduced as a major (about 50%) component ofthe piperylene rich feed stream. Various diluents which are inert inthat they do not enter into the polymerization reaction may be used.Representative examples of inert diluents are aliphatic hydrocarbonssuch as pentane, hexane, and heptane, aromatic hydrocarbons such astoluene and benzene, and unreacted residual hydrocarbons from thereaction.

A wide range of temperatures can be used for the polymerizationreaction. The polymerization can be carried out at temperatures in therange of from about -20° C. to about 100° C., although usually thereaction is carried out at a temperature in the range of from about 0°C. to about 50° C. The polymerization reaction pressure is not criticaland may be atmospheric or above or below atmospheric pressure.Generally, a satisfactory polymerization can be conducted when thereaction is carried out at about autogeneous pressure developed by thereactor under the operating conditions used. The time of the reaction isnot generally critical and reaction times can vary from a few minutes to12 hours or more.

The yield and softening point of the final resin ranges from 20 to 45percent and 90° C. to 100° C., respectively.

The improved product of this invention made by polymerization of theenriched modifier stream in conjunction with the piperylene containingstream results in a hydrocarbon resin with from 40-50 weight percentunits derived from piperylene and 15-20 weight percent units derivedfrom 2-methylbutenes. The product of this invention, when madeexclusively from steam cracked naphtha and after removal of the bulk ofthe isoprene, contains primarily 2-methylbutene-2 as the methylbutenemodifier. The 2-methylbutene-2 to 2-methylbutene-1 ratio in the enrichedmodifier is at least 10. The product of the invention has softeningpoints of 90°-100° C. and molecular weights lower than the unmodifiedresin. Molecular weights, as Mw, of about 1200 as measured by GelPermeation Chromatography (GPC) were obtained for the products resinsaccording to the inventive process when using the enriched modifierstream, as isomerized, in the preparation of the resin. Also for resinsprepared from the process using the unmodified modifier stream, resinswith similar molecular weight but lower softening points were obtainedas will be seen in the example.

In contrast, resins obtained from polymerization of the piperylene richfeedstream only (no addition of the modifier stream) have Mw of about1600 - undesirably high.

EXAMPLES OF THE INVENTION

The best mode of the invention described herein is exemplified by thefollowing sequential processes of isomerization, admixing, polymerizingand resin recovery:

(a) A branched olefin modifier stream (obtained from a solvent extractedC₅ -C₆ isoprene rich stream of steam cracked naphtha) typically composedof 3 wt.% isoprene, 57 wt.% C₅ -C₆ olefins, 35 wt.% 2-methylbutene-1 and5 wt.% 2-methylbutene-2 was admixed with an isomerization catalyst,Amberlyst IR-15 available from Rohm and Haas, Philadelphia, Pa., at arate of 1 volume of said stream per volume of catalyst per hour at 40°C. to provide the branched olefin enriched modifier stream. Theresultant enriched modifier stream had a typical composition of 3 wt.%isoprene, 57 wt.% C₅ -C₆ olefins, 5 wt.% of 2-methylbutene-1 and 35 wt.%of 2-methylbutene-2;

(b) 4 volume percent of said branched olefin enriched modifier streamwas admixed into a piperylene rich feedstream (15 wt.% piperylene withminor amount of isoprene, 25 wt.% of C₅ -C₆ olefins, 4 wt.% of2-methylbutene-2 and balance diluent benzene) to provide the feedstockfor resinification;

(c) The resulting feedstock was mixed with 1 wt.% of aluminum chloridecatalyst at a temperature of 50° C. and residence time in excess of 30minutes; and,

(d) whereby a hydrocarbon resin was produced and recovered having asoftening point of 96° C., a cloud point of below 90° C. and a color of6 Gardner units. The cloud point determination is by visual observationof the onset of clouding of a solution of 2 wt. part resin, 1 wt. partof paraffin wax having a m.p. of 60° C. and 2 wt. parts of ethylenevinyl acetate polymer (28% vinyl acetate) heated to 150° C. and allowedto cool in air with stirring.

In contrast, when the aforesaid branched olefin modifier stream is notenriched (no isomerization step) and admixed at a 4 volume percent intosaid piperylene rich feed stream for resinification according to theabove process, a hydrocarbon resin was produced having a softening pointof 89° C., a cloud point of below 90° C. and a color of 6 Gardner units.

The softening point is determined by ASTM procedure E28-67.

It is seen that the product of the invention has a softening point 7° C.higher than a product obtained under a process following prior art typeteachings.

Not only are the products of the invention superior to known products,but the process by which they are made, better utilizes feeds availablefrom cracking, particularly steam cracking, of heavy petroleumfractions.

The invention in its broader aspect is not limited to the specificdetails shown and described and departures may be made from such detailswithout departing from the principles of the invention and withoutsacrificing its chief advantages.

What is claimed is:
 1. A hydrocarbon resin comprising from 40 to 50weight percent units derived from piperylene, 15 to 20 weight percentunits derived from 2-methylbutenes and the balance derived from otherolefinic compounds having from 5 to 6 carbons, said 2-methylbutenesconsisting essentially as the 2-methylbutene-2 isomer and the2-methylbutene-1 isomer in a weight ratio of the former isomer to thelatter isomer being greater than 10 whereby said resin has a softeningpoint of at least 90° C.
 2. The hydrocarbon resin according to claim 1wherein said isomer weight ratio of 2-methylbutene-2 to 2-methylbutene-1ranges from 15 to 100 whereby said resin has a softening point of from90° C. to 100° C.
 3. The hydrocarbon resin according to claim 1 whereinsaid isomer weight ratio of 2-methylbutene-2 to 2-methylbutene-1 rangesfrom 18 to 30 whereby said resin has a softening point of from 90° C. to100° C.